Conventional “channel type” flush valves use a pressure difference to open or close a water outlet. The automatic flush valve controlled by electronic means also adopts channel type flushing. The conventional automatic flush valve uses a small channeling water flow to generate a pressure difference to control opening and closing of the water outlet to flush a greater amount of water. In practice, while a small amount of electric power may control a smaller pressure release hole to channel a small water flow, the small water flow cannot quickly release the pressure and the main water ball cannot be lifted quickly to flush the water rapidly at a greater amount. Therefore water discharge time of the small water flow has to be extended. As a result, flush time has to be lengthened and water consumption has to increase to generate adequate siphonic effect to flush the wastes in toilet away. More details of the structure and function of the conventional flush apparatus are elaborated as follow:
1. R.O.C. patent publication No. 310737 entitled “Manual and automatic flush valve” submitted by the Applicant has a solenoid stem which is movable up and down to open and close a pressure release hole formed in an annular trough of an intermediate board. An automatic detected water pressure is released through the pressure release hole to allow a smaller water flow to control a larger water flow. However it is applicable only to the urinary, not desirable for flushing the toilet. As the toilet needs a greater amount of flush water, using the up and down movement of the solenoid valve stem to open and close the pressure release hole of the intermediate board can lift the main water ball quickly, but it still cannot generate a great amount of water in a given time due to the urinary does not need a greater amount of water. Hence it is not suitable for flushing toilets that require a great amount of discharge water to generate the siphonic effect.
2. There are some other conventional toilet flushing apparatus that adopt a sensor to detect user's body movement. For instance, R.O.C patent No. 174370 entitled “Automatic detection flushing apparatus for toilets” and No. 258240 entitled “Attached automatic flushing device for toilets” disclose a technique which includes a control circuit built on a membrane sensor. However, the membrane is easily damaged by the vibration of water pressure. The valve also is quite bulky. There is still room for improvement.
In view of the problems set forth above, to design a flush valve which does not consume electric power in a given size, and can release the pressure quickly in a given time to flush effectively is an issue pursued in the industry, and also is a goal of the present invention.